NCMP Analysis (2021/22 to 2023/24)

This report was produced by Birmingham Public Health (Knowledge Team). For support or feedback please contact publichealthintelligence@birmingham.gov.uk

Main Messages

This report presents analysis of data from the National Child Measurement Program (NCMP) for children in Birmingham. The majority of analyses combine the 3 most recent annual cohorts of NCMP data (2021/2022, 2022/2023 and 2023/2024) to ensure results are robust.

In summary, deprivation, ethnicity and gender all have varying levels of impact on the prevalence of overweight and obesity. The effect of deprivation is the simplest - prevalence of obesity is highest in the most deprived areas of Birmingham. Ethnicity and gender also affect prevalence in more complex ways, described below.

In Reception-age children:

Prevalence of overweight and obesity has decreased significantly in Birmingham between the 2013-16 and 2021-24 periods (from a high of 24.1% in the 2016-19 period to 22.4% in the 2021-24 period).
In the most recent three-year period, prevalence of overweight and obesity is significantly higher in Birmingham (22.4%) when compared to the England average (21.9%).
Children of both genders who live in the most deprived areas have significantly higher prevalence of overweight and obesity (23.6%) compared to children who live in the least deprived areas (16.1%).
Asian children have significantly lower prevalence of overweight and obesity (19.9%) than White (25.0%), Black (24.3%) and Mixed ethnicity (25.1%) children (all of whom have similar prevalence).
Asian children have significantly higher prevalence of underweight (3.0%) than children of Black (1.5%), Mixed (1.2%) and Other (1.5%) ethnicities. White children have significantly lower prevalence of underweight (0.6%) than all other ethnicities.
Prevalence of short stature is significantly higher in girls (1.9%) than boys (1.5%), and is lowest in Black and Mixed ethnicity children.

In Year 6-age children:

Prevalence of overweight and obesity has significantly increased in Birmingham between the 2013-16 and 2021-24 periods (from 39.4% to 41.3%).
In the most recent three-year period, prevalence of overweight and obesity is significantly higher in Birmingham (41.3%) when compared to the England average (36.7%).
Children of both genders who live in the most deprived areas have significantly higher prevalence of overweight and obesity (43.5%) compared to children who live in the least deprived areas (27.9%).
Asian (42.6%), Black (43.6%) and Mixed ethnicity (42.6%) children have significantly higher prevalence of overweight and obesity than White children (38.9%).
Asian children have significantly higher prevalence of underweight (3.5%) than children of all other ethnicities (Black: 1.8%; Mixed:1.4%; Other: 2.2%; White: 1.2%). Prevalence in White children is significantly lower than in Black or Mixed ethnicity children.
Prevalence of short stature has decreased significantly between the 2013-6 (1.4%) and 2021-24 (0.9%) periods, with Black children having lowest prevalence.

Introduction

Welcome to this analysis report for the National Child Measurement Program (NCMP). The NCMP is essential for monitoring the prevalence of overweight and obesity in children, both in Birmingham and nationally. It also provides insights into the prevalence of short stature. Children are measured each year in Reception (aged 4-5 years) and Year 6 (aged 10-11 years).

The majority of the analysis in this report combines data from the past three years (2021/2022, 2022/2023 and 2023/2024) to give a three-year-combined period (2021-24). This improves data robustness and allows more concrete conclusions to be drawn. Where time series are plotted, three-year periods are also used. Data from the 2020/21 academic year has not been used due to very low participation rates as a result of the Covid-19 pandemic.

Data Suppression

In some instances, data has been suppressed in accordance with NHS Digital disclosure control recommendations:

Any value based on a numerator of 7 or less has been suppressed
Percentages and rates have been calculated using rounded data (e.g. the numerator and denominator for a percentage have been rounded to the nearest 5).

Participation

In the 2021-24 period, an average of 96.8% of eligible Reception pupils (41555 children total) and an average of 95.4% of eligible Year 6 pupils (46500 children total) in Birmingham were measured as part of the NCMP.

Confidence intervals

Where possible, 95% confidence intervals have been included. All summary statistics have a degree of uncertainty and confidence intervals help visualise this. 95 times out of 100, the true value will fall somewhere within the range given by the confidence intervals.

Confidence intervals are displayed as one or both of:

error bars on a chart, showing the upper and lower limits of the range
a range in the tooltip of a chart (e.g. 45.1% (43.2 - 46.3%) means the calculated value is 45.1%, with an upper confidence interval of 43.2% and a lower interval of 46.3%.)

In the written commentary in this report, comparisons between groups and over time have been statistically tested to determine whether differences are likely to be genuine (i.e. statistically significant) or the result of random natural variation. Only statistically significant differences have been described with terms such as “higher”, “lower”, “increase” or “decrease”. Where non-significant differences are described they are clearly marked.

Prevalence of Overweight and Obesity

It has been well-understood for many years that children who are overweight or obese are more likely to become overweight or obese adults, and that the probability of this increases with age¹. Overweight and obesity in adulthood is associated with multiple health conditions, and places a significant burden on health services.

This section of the report investigates the prevalence of overweight and obesity (and, where relevant, underweight) in children in Birmingham, and the socioeconomic and demographic factors influencing this.

BMI thresholds for children are assigned based on the British 1990 Growth Reference (UK90), which describes the expected pattern of growth for children at different ages and by sex.

At a population level, BMI categories are assigned as such:

Underweight: BMI less than the 2nd centile of the UK90 according to age and sex
Healthy weight: BMI between the 2nd and 85th centiles
Overweight: BMI between the 85th and 95th centiles
Obese: BMI on or above the 95th centile

Overview

This section looks at Birmingham as a whole, providing a broad overview of how the city is performing. It also compares Birmingham to England.

BMI Category breakdown

Figure 1. Percentage of children in each BMI category, by school year (2021-24 period)

The proportion of children who are obese is much higher (more than double) in Year 6 than in Reception. Prevalence of overweight is also higher in Year 6 children, as is prevalence of underweight.

Prevalence of overweight/obesity, compared to England

Figure 2. Prevalence of overweight and obesity in Birmingham and England, by school year (2021-24 period)

Birmingham has higher levels of overweight and obesity than the England average for both Reception and Year 6 pupils.

Prevalence of overweight/obesity, compared to England, over time

Figures 3a and 3b show the prevalence of overweight and obesity in Birmingham and England over time, split by school year. Use the tabs to move between the figures.

Figure 3a. Percentage of Reception children who are overweight or obese over time, compared to England

Prevalence of overweight and obesity has decreased in Birmingham since 2013-16. Birmingham continues to have higher prevalence than the England average, although the gap has got smaller and during the 2019-23 combined period Birmingham had similar prevalence to England for the first time.

Figure 3b. Percentage of Year 6 children who are overweight or obese over time, compared to England

Prevalence of overweight and obesity has increased in Birmingham since 2013-16, following a trend similar to England. Birmingham continues to have higher prevalence than the England average, although the gap has got smaller.

By Deprivation

This section investigates the effect of deprivation on BMI category. There is a strong correlation between obesity and deprivation, with children living in the most deprived areas experiencing a higher prevalence of obesity than their less deprived peers².

Deprivation is measured here using the Income Deprivation Affecting Children Index (IDACI), which measures the proportion of children aged 0-15 living in income-deprived families in a small, defined area. These small areas are divided according to their deprivation rank into five quintiles, ranging from the most deprived areas (IDACI quintile 1) to the least deprived areas (IDACI quintile 5). IDACI quintile is calculated using the postcode of a child’s home address.

Important Note

It is important to note that the majority (over 60%) of children included in this analysis are classed as living in IDACI quintile 1, while only around 4% live in quintile 5. As a result, the sample sizes for quintiles 3, 4 and 5 are relatively small, meaning confidence intervals are generally large and statistical significance is harder to achieve. This should be taken into account when e.g. considering changes over time or comparing groups.

BMI Category by IDACI Quintile

Figures 4a and 4b show the percentage of children in each IDACI quintile who fall into each of the four BMI categories (underweight, healthy weight, overweight and obese), for the 3-year period 2021-24. Use the tabs to move between the figures.

Figure 4a. Percentage of Reception children in each BMI category by IDACI quintile

Prevalence of obesity increases as deprivation increases, while prevalence of overweight and underweight are roughly similar at each quintile.

Figure 4a. Percentage of Year 6 children in each BMI category by IDACI quintile

Prevalence of obesity increases as deprivation increases, while prevalence of overweight and underweight are roughly similar at each quintile.

Overweight/Obese by IDACI Quintile and Gender

Figures 5a and 5b show the percentage of girls and boys in each IDACI quintile who are classed as either overweight or obese, for the 3-year period 2021-24. Use the tabs to move between the figures.

Figure 5a. Percentage of Reception children who are overweight or obese by IDACI quintile and gender

There is no significant difference in prevalence of overweight or obesity between boys and girls at any level of deprivation.

Figure 5b. Percentage of Year 6 children who are overweight or obese by IDACI quintile and gender

A higher proportion of boys than girls are overweight or obese in more deprived areas (quintiles 1, 2 and 3). In the two least deprived quintiles, there is no significant difference in prevalence between boys and girls.

Deprivation gap over time

Figure 6(a-h) shows the percentage of children in IDACI quintiles 1 and 5 who are classed as underweight, overweight or obese for 3-year rolling periods over time. Use the tabs to move between the figures.

Figure 6a. Percentage of Reception children who are underweight by IDACI quintile, over time

For the past ten years, prevalence of underweight has been higher in children from the most deprived areas, but during most periods this difference was not statistically significant. There has been a significant increase in prevalence of underweight in children in IDACI quintile 1 between 2013-16 and 2021-24. The ‘gap’ between the two quintiles has no discernible trend.

Figure 6b. Percentage of Reception children who are overweight by IDACI quintile, over time

For the past ten years, prevalence of overweight has been higher in children from the most deprived areas, but during most periods this difference was not statistically significant. There has been a significant decrease in prevalence of overweight in children in IDACI quintile 1 between 2013-16 and 2021-24. The ‘gap’ between the two quintiles has no discernible trend.

Figure 6c. Percentage of Reception children who are obese by IDACI quintile, over time

For the past ten years, prevalence of obesity has been higher in children from the most deprived areas, by an average of around 6%. The ‘gap’ between the two quintiles appears to be getting smaller - obesity prevalence in children in IDACI quintile 1 has stayed roughly the same between 2013-16 and 2021-24, while prevalence in children in IDACI quintile 5 has increased, though not significantly.

Figure 6d. Percentage of Reception children who are overweight or obese by IDACI quintile, over time

For the past ten years, prevalence of overweight and obesity has been higher in children from the most deprived areas, by an average of around 7%. There has been a decrease in prevalence of overweight and obesity in children in IDACI quintile 1 between 2014-17 and 2021-24. The ‘gap’ between the two quintiles has no discernible trend.

Figure 6e. Percentage of Year 6 children who are underweight by IDACI quintile, over time

For most of the past ten years, prevalence of underweight has been higher in children from the most deprived areas, but this difference was not statistically significant. There has been a significant increase in prevalence of underweight in children in IDACI quintile 1 between 2013-16 and 2021-24. The ‘gap’ between the two quintiles has no discernible trend.

Figure 6f. Percentage of Year 6 children who are overweight by IDACI quintile, over time

Over the past ten years there has been a decrease in prevalence of overweight in children from the least deprived areas, and a non-significant increase in prevalence of overweight in children from the most deprived areas. As a result, in recent years (from the 2018-22 period onward) the ‘gap’ between the quintiles has reversed, with prevalence of overweight being higher in children in IDACI quintile 5. However, this difference is not statistically significant.

Figure 6g. Percentage of Year 6 children who are obese by IDACI quintile, over time

For the past ten years, prevalence of obesity has been higher in children from the most deprived areas. The ‘gap’ between the two quintiles appears to be getting larger - obesity prevalence in children in IDACI quintile 1 has increased between 2013-16 and 2021-24, while prevalence in children in IDACI quintile 5 has stayed roughly the same.

Figure 6h. Percentage of Year 6 children who are overweight or obese by IDACI quintile, over time

For the past ten years, prevalence of overweight and obesity has been higher in children from the most deprived areas. The ‘gap’ between the two quintiles appears to be getting slightly larger - overweight and obesity prevalence in children in IDACI quintile 1 has increased between 2013-16 and 2021-24, while prevalence in children in IDACI quintile 5 has stayed roughly the same.

By Ethnicity

This section investigates the effect of ethnicity on BMI category. There are known disparities in weight status by ethnicity at a national level, with Black and Asian children typically having higher prevalence of obesity than children of White ethnicity³. The same is broadly true in Birmingham for the Year 6 age group, though not for Reception-age children.

Ethnicity is grouped at the broadest possible level to improve data robustness (see caveat below). The groups used are Asian, Black, Mixed, Other and White, plus a sixth category, Unknown, which is used when data on ethnicity is not recorded. The Unknown category has been included in graphs but is not included in written commentary.

Important Note

It is important to note that some ethnicities are better represented than others in the data. Asian and White children make up the biggest cohorts, making up around 35% and 29% of children respectively. The smallest groups are children of Mixed or Other ethnicity, each representing less than 7% of children, while around 11% of children are Black. As a result, the sample sizes for Black, Mixed and Other ethnicities are relatively small, meaning confidence intervals are generally large and statistical significance is harder to achieve. This should be taken into account when e.g. considering changes over time or comparing groups.

BMI Category by Ethnicity

Figures 7a and 7b show the percentage of children who fall into each of the four BMI categories (underweight, healthy weight, overweight and obese), split by ethnicity, for the 3-year period 2021-24. Use the tabs to move between the figures.

Figure 7a. Percentage of Reception children in each BMI category by ethnicity

Prevalence of obesity is highest in Black and Mixed ethnicity children, while prevalence of overweight is highest in White and Mixed ethnicity children. Asian children have the highest prevalence of underweight.

Figure 7b. Percentage of Year 6 children in each BMI category by ethnicity

Prevalence of obesity is highest in Black, Asian and Mixed ethnicity children, while prevalence of overweight is roughly the same across ethnicities. Asian children have the highest prevalence of underweight.

Overweight/Obese by Ethnicity and Gender

Figures 8a and 8b show the percentage of girls and boys who are classed as either overweight or obese, split by ethnicity, for the 3-year period 2021-24. Use the tabs to move between the figures.

Figure 8a. Percentage of Reception children who are overweight or obese by ethnicity and gender

For children of most ethnicities, there is no significant difference in prevalence of overweight or obesity between boys and girls. However, Asian girls have higher prevalence than Asian boys.

Figure 8b. Percentage of Year 6 children who are overweight or obese by ethnicity and gender

Boys of White, Asian or Other ethnicity have a higher prevalence of overweight or obesity than their female counterparts. The gap between boys and girls is largest in Asian children. For Black and Mixed ethnicity children there is no significant difference in prevalence between the genders.

Trends by Ethnicity

Figure 9(a-h) shows the percentage of children of each ethnicity who are classed as underweight, overweight or obese for 3-year rolling periods over time. Use the tabs to move between the figures.

Note

Note that these figures allow you to select which traces are visible, for ease of comparison. To hide a trace, click on the corresponding symbol in the legend. For example, to hide values for children of unknown ethnicity, click on the blue symbol labelled ‘Unknown’. To view a single trace and hide all others, double click on its symbol in the legend.

Figure 9a. Percentage of Reception children who are underweight by ethnicity, over time

Figure 9b. Percentage of Reception children who are overweight by ethnicity, over time

Over the past ten years, prevalence of overweight has generally been similar (i.e. not significantly different) in children of White, Black, Mixed and other ethnicities, with no significant changes in prevalence over time. Prevalence of overweight in Asian children has remained lower than all other groups and has seen a small but significant decrease between 2013-16 and 2021-24.

Figure 9c. Percentage of Reception children who are obese by ethnicity, over time

In the most recent period (2021-24) prevalence of obesity is statistically similar (i.e. not significantly different) across all ethnicities. However, in 2013-16, Black children had a higher prevalence than all other ethnicities. Although prevalence of obesity in Black children appears to have decreased over the past ten years, while prevalence in White children appears to have increased, these changes are not statistically significant.

Figure 9d. Percentage of Reception children who are overweight or obese by ethnicity, over time

Over the past ten years, prevalence of overweight and obesity has generally been similar (i.e. not significantly different) in children of White, Black, Mixed and other ethnicities. However, the proportion of Black children who are overweight or obese has decreased between 2013-16 and 2021/24. Prevalence of overweight and obesity in Asian children has remained lower than all other groups since 2015-18 and has seen a small but significant decrease between this period and 2021-24.

Figure 9e. Percentage of Year 6 children who are underweight by ethnicity, over time

Asian children have consistently had higher prevalence of underweight than children of all other ethnicities for the past ten years, with no significant change in prevalence. Prevalence of underweight has generally been similar (i.e. not significantly different) in children of all other ethnicities, although children of Black and Other ethnicities have had a higher prevalence than White children since 2016-19. Prevalence of underweight in Black children has increased by a small but significant amount over the past ten years.

Figure 9f. Percentage of Year 6 children who are overweight by ethnicity, over time

Over the past ten years, prevalence of overweight has generally been similar (i.e. not significantly different) across all ethnicities. Prevalence of overweight in Black children has decreased between 2013-16 and 2021-24, with all other ethnicities seeing no significant change in prevalence.

Figure 9g. Percentage of Year 6 children who are obese by ethnicity, over time

Over the past ten years, prevalence of overweight has remained lower in children of White ethnicity than those of Asian, Black and Mixed ethnicities. However, prevalence of overweight in White children has increased in this time. In the most recent period (2021-24), children of Other ethnicities have a prevalence which is similar to White children, and lower than Asian and Black children.

Figure 9h. Percentage of Year 6 children who are overweight or obese by ethnicity, over time

Over the past ten years, prevalence of overweight and obesity has remained lower in children of White ethnicity than those of Asian, Black and Mixed ethnicities. However, prevalence of overweight and obesity in White children has increased in this time.

By Deprivation and Ethnicity

This section uses inequality matrices to examine the interaction of deprivation and ethnicity on BMI category. Looking at these categories in combination is important to better understand which groups are most at risk of overweight. Use the tabs to move between the figures.

Note

The heatmap shows the percentage of children in a group who fall into the relevant BMI category. The higher the proportion, the darker the tile. Groups with a prevalence which is significantly higher or lower than the Birmingham average are indicated with an up arrow (↑) or down arrow (↓) respectively. Groups with a prevalence statistically similar to the average are indicated with a dash (-).

Note that IDACI quintiles 3-5 have been combined into a single category to improve data robustness.

Figure 10a. Inequality matrix of deprivation and ethnicity, for percentage of Reception children who are underweight (2021-24 period)

Asian children at all levels of deprivation experience a higher prevalence of underweight than the Birmingham average. White children at all levels of deprivation, as well as children of Mixed and Other ethnicities in IDACI quintile 1, have a lower prevalence of underweight than average.

Figure 10b. Inequality matrix of deprivation and ethnicity, for percentage of Reception children who are overweight (2021-24 period)

Asian children at all levels of deprivation experience a lower prevalence of overweight compared to the average. White children at all levels of deprivation, and Mixed ethnicity children in IDACI quintile 1, have a higher prevalence of overweight than average, with prevalence highest in the most deprived White children.

Figure 10c. Inequality matrix of deprivation and ethnicity, for percentage of Reception children who are obese (2021-24 period)

Prevalence of obesity is higher than the Birmingham average in Mixed and White children in quintile 1, and Black children in quintile 2. White and Asian children in the least deprived quintiles have lower prevalence of obesity than average. Black children in quintile 2 experience the highest prevalence of all groups.

Figure 10d. Inequality matrix of deprivation and ethnicity, for percentage of Reception children who are overweight or obese (2021-24 period)

White children in IDACI quintiles 1 and 2 have higher prevalence of overweight and obesity than average. Black children in quintile 2, and Mixed ethnicity children in quintile 1, also have higher prevalence. Asian children at all levels of deprivation experience lower prevalence of overweight and obesity than average, as do children of White and Other ethnicities in the least deprived areas.

Figure 10e. Inequality matrix of deprivation and ethnicity, for percentage of Year 6 children who are underweight (2021-24 period)

Asian children at all levels of deprivation experience a higher prevalence of underweight than the Birmingham average. White children at all levels of deprivation, as well as Black children in IDACI quintile 1, have a lower prevalence of underweight than average. The highest prevalence of underweight is seen in Asian children in quintiles 3-5.

Figure 10f. Inequality matrix of deprivation and ethnicity, for percentage of Year 6 children who are overweight (2021-24 period)

Children of Mixed ethnicity experience lower prevalence of overweight than the Birmingham average. Almost all other groups do not differ from the average, though children of Unknown ethnicity do have higher prevalence of overweight.

Figure 10g. Inequality matrix of deprivation and ethnicity, for percentage of Year 6 children who are obese (2021-24 period)

Children of Asian, Black, White and Mixed ethnicities in IDACI quintile 1, as well as Black children in quintile 2, experience prevalence of obesity than the Birmingham average. Children of Asian, White and Other ethnicities in quintiles 3-5 have lower levels of obesity. Prevalence is highest in Black children in IDACI quintile 2.

Figure 10h. Inequality matrix of deprivation and ethnicity, for percentage of Year 6 children who are overweight or obese (2021-24 period)

Prevalence of overweight and obesity is higher than average in children of Asian, Black, White and Mixed ethnicities in IDACI quintile 1, and in Black children in quintile 2. Children of Asian, Black and Other ethnicities in quintiles 3-5, and White children in quintile 2, have lower prevalence. Prevalence of overweight and obesity is highest in Black children in IDACI quintile 2.

By Geography

This section looks at how prevalence of overweight and obesity is distributed geographically using interactive maps.

Overweight/Obese Prevalence - Heatmap

Figures 11a and 11b show how prevalence of overweight and obesity varies across the city. A darker colour indicates a higher prevalence of overweight and obesity in that area. Use the tabs to move between the figures.

The boundaries of the MSOAs, wards and parliamentary constituencies visualised in these maps are not coterminous (i.e. they do not overlap perfectly). As a result, constituencies should only be compared with constituencies, wards with wards and so on.

Note

To explore the map, zoom in and out with the zoom buttons at the top left. The locations of primary schools are marked - hover over a marker to see the name of the school, or remove the markers by unticking the layer in the box in the top right. This box also allows the user to choose whether prevalence is mapped by MSOA, electoral ward or parliamentary constituency (also known as districts).

Figure 11a. Percentage of Reception children who are overweight or obese, by MSOA/ward/constituency (2021-24 period)

Figure 11a. Percentage of Year 6 children who are overweight or obese, by MSOA/ward/constituency (2021-24 period)

Overweight/Obese Prevalence - Significance Map

Figures 12a and 12b show how prevalence of overweight and obesity varies across the city. Areas are colour-coded to indicate whether prevalence is higher (orange), similar to (yellow) or lower (green) than the Birmingham average. Use the tabs to move between the figures.

Note

Figure 12a. Percentage of Reception children who are overweight or obese, by MSOA/ward/constituency (2021-24 period)

N.B. The Birmingham average for Reception is 22.4%.

Figure 13b. Percentage of Year 6 children who are overweight or obese, by MSOA/ward/constituency (2021-24 period)

N.B. The Birmingham average for Year 6 is 41.2%.

Changes in BMI Category

This section presents analysis looking at how children have moved between BMI categories from Reception to Year 6.

The NCMP dataset contains information such as name, NHS number and date of birth which allow a child’s Reception measurement to be linked to their subsequent measurement in Year 6. Because the analysis tracks individual children, clinical BMI thresholds were used to assign BMI category. As a result, the proportions of children in each BMI category will differ from the population level prevalence estimates presented elsewhere in this analysis.

This analysis combines data from three cohorts of children to ensure estimates are robust:

Children measured in Reception in 2014/15, and in Year 6 in 2021/22
Children measured in Reception in 2015/16, and in Year 6 in 2022/23
Children measured in Reception in 2016/17, and in Year 6 in 2023/24

Figures 13(a-c) show the changes in child BMI category from Reception to Year 6. Note that some bars do not add up to 100% as a result of small number suppression. Use the tabs to move between figures.

Figure 13a. Changes in child BMI category from Reception to Year 6.

The majority of children who were healthy weight in Reception remained healthy weight in Year 6, with around a quarter of the cohort moving to a higher BMI category. Of children who were in a higher BMI category, the majority remained in a higher BMI category - this proportion was highest in children who were obese in Reception, of whom 95% remained either overweight or obese. Meanwhile, around a quarter of children who were overweight moved to a healthy weight. Only a very small proportion of children who were underweight moved to being overweight or obese; the majority moved to healthy weight, with just over a third remaining underweight.

Figure 13b. Changes in child BMI category from Reception to Year 6, by gender.

Boys were less likely to remain a healthy weight than girls, and more likely to either remain obese or move from being overweight to being obese.

A higher proportion of girls than boys who were a healthy weight in Reception remained a healthy weight in Year 6, with a higher proportion of boys moving to being obese. Of children who were overweight in Reception, a higher proportion of boys moved to being obese, while similar proportions of boys and girls moved to healthy weight. A higher proportion of boys who were obese in Reception remained obese, with girls being more likely than boys to move down a category to be overweight.

Figure 13c. Changes in child BMI category from Reception to Year 6, by IDACI quintile (grouped).

Children in more deprived areas were less likely to remain a healthy weight and more likely to move from overweight to obese.

Of children living in IDACI quintile 1 who were a healthy weight in Reception, a lower proportion remained a healthy weight than children in quintiles 3-5, while a higher proportion moved to being obese. A higher proportion of children living in IDACI quintiles 3-5 who were overweight in Reception moved to healthy weight than children in quintile 1, while a lower proportion moved to being obese.There were no significant differences between quintiles in children who were underweight or obese in Reception, likely due to small sample sizes.

Prevalence of Short Stature

Short stature is defined as having a height below the 2nd centile of the UK90 growth reference, according to age and gender. Around 80% of variance in height is attributable to genetic factors, leaving 20% explained by environmental influences such as diet and nutrition, living conditions, parental smoking and childhood illness⁴.

This section explores the prevalence of short stature in children in Birmingham, and some of the factors which may affect this.

Overview

Figure 14. Percentage of children classed as having short stature by year group, over time

Prevalence of short stature is higher in Reception-age children, where there has been no significant change over the past ten years. However, there has been a decrease in prevalence of short stature in Year 6 children in this time.

Gender

Figure 15. Percentage of children classed as having short stature, by gender and year group (2021-24 period)

In Reception-age children, girls have higher prevalence of short stature than boys. In Year 6 children, there is no significant difference between the genders.

Deprivation

Figure 16. Percentage of children classed as having short stature, by IDACI quintile and year group (2021-24 period)

In both year groups prevalence of short stature does not differ significantly between quintiles, suggesting short stature is not strongly affected by deprivation.

Ethnicity

Figure 17. Percentage of children classed as having short stature, by ethnicity and year group (2021-24 period)

Children of Asian, White and Other ethnicity in Reception have higher prevalence of short stature than Black and Mixed ethnicity children. In Year 6, Black children have lower prevalence of short stature than children of Asian and Other ethnicity.

Footnotes

Serdula MK, Ivery D, Coates RJ, Freedman DS, Williamson DF, Byers T. Do obese children become obese adults? A review of the literature. Preventative Medicine 1993↩︎
NHS Digital, National Child Measurement Programme, England, 2023/24↩︎
NHS Digital, National Child Measurement Programme, England, 2023/24↩︎
McEvoy BP, Visscher PM. Genetics of human height. Econ Hum Biol. 2009↩︎